Delivery system assemblies for implantable medical devices

ABSTRACT

An inner subassembly of a delivery system assembly extends within a lumen of an elongate outer tube of the assembly, and includes a flared distal end, which is preferably configured to conform to a proximal end of an implantable medical device; a distal-most portion of the outer tube is sized to contain both the flared distal end and an entirety of the medical device. The inner subassembly includes a core, an elongate pull-wire, extending along the core, and a sheath surrounding the pull-wire and the core; the sheath includes a slot opening that allows the pull-wire to pass laterally therethrough. The assembly preferably has a pre-formed curvature along a length of the sheath, and the slot opening extends along the pre-formed curvature. The outer tube is longitudinally moveable relative to the inner subassembly, for example, to deploy the medical device.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to the following co-pending andcommonly assigned United States Patent Applications: application Ser.No. 13/239,990, which is entitled DELIVERY SYSTEM ASSEMBLIES FORIMPLANTABLE MEDICAL DEVICES, and which was filed on Sep. 22, 2011application Ser. No. 13/279,835, which is entitled DELIVERY SYSTEMASSEMBLIES AND ASSOCIATED METHODS FOR IMPLANTABLE MEDICAL DEVICES, andwhich was filed on Oct. 24, 2011; application Ser. No. 13/298,973, whichis entitled DELIVERY SYSTEM ASSEMBLIES AND ASSOCIATED METHODS FORIMPLANTABLE MEDICAL DEVICES, and which was filed on even date herewith;and application Ser. No. 13/219,279, which is entitled HOLDING MEMBERSFOR IMPLANTABLE CARDIAC STIMULATION DEVICES, and which was filed on Aug.26, 2011.

FIELD OF THE DISCLOSURE

The present invention pertains to delivery system assemblies forimplantable medical devices, and more particularly to delivery systemassemblies configured to facilitate percutaneous transvenous deploymentof relatively compact implantable medical devices.

BACKGROUND

The traditional implantable cardiac pacemaker includes a pulse generatordevice to which one or more flexible elongate lead wires are coupled.The device is typically implanted in a subcutaneous pocket, remote fromthe heart, and each of the one or more lead wires extends therefrom to acorresponding electrode, coupled thereto and positioned at a pacingsite, either endocardial or epicardial. Mechanical complications and/orMRI compatibility issues, which are sometimes associated with elongatelead wires and well known to those skilled in the art, have motivatedthe development of cardiac pacing devices that are wholly containedwithin a relatively compact package for implant in close proximity tothe pacing site, for example, within the right ventricle (RV) of theheart. With reference to FIG. 1, such a device 100 is illustrated,wherein pace/sense electrodes 111, 112 are formed on an exterior surfaceof an enclosure that hermetically contains a pulse generator includingpulse generator electronics and a power source. FIG. 1 illustrates afixation member 115 mounted to an end of the enclosure of device 100, inproximity to electrode 111, in order to fix, or secure electrode 111against the endocardial surface in the apex of the RV. The enclosure ispreferably formed from a biocompatible and biostable metal such astitanium, which may be overlaid with an insulative layer, for example,medical grade polyurethane or silicone, except where electrode 112 isformed as an exposed portion of the enclosure. A hermetic feedthroughassembly (not shown), such as any known to those skilled in the art,couples electrode 111 to the pulse generator contained within theenclosure of device 100.

FIG. 1 further illustrates a distal portion of a standard guidingcatheter 150 having been maneuvered up through the inferior vena cava(IVC) and into the RV from the right atrium (RA), according to methodsknown in the art of interventional cardiology. Although catheter 150 maybe employed to deliver device 100 to the RV, for implant, moresophisticated delivery systems that facilitate improved navigation anddeployment more suitable for relatively compact implantable devices,like device 100, are desired.

SUMMARY

A delivery system assembly, according to embodiments of the presentinvention, includes an inner subassembly and an outer subassembly and isdeflectable and retractable for deployment of an implantable medicaldevice. An elongate core of the inner subassembly extends within a lumenof an elongate outer tube of the outer subassembly, and the innersubassembly further includes an elongate pull-wire extending along thecore, and a sheath, which extends around the pull-wire and the core,within the lumen formed by the outer tube. The elongate core preferablyincludes a flared distal end, which is conformable to a proximal end ofthe medical device; and a distal-most portion of the outer tube, ispreferably sized to contain both the flared distal end of the core andan entirety of the medical device.

The pull-wire may be actuated to deflect the flared distal end of thecore along with distal-most portion of the outer tube, so that a distalopening of the outer tube lumen may be directed toward a target implantsite for deployment of the contained medical device therethrough, forexample, by retraction of the outer tube, relative to the innersubassembly. The sheath preferably includes a slot opening that islocated and sized to allow the pull-wire to pass laterally therethrough.According to some preferred embodiments, the assembly has a pre-formedcurvature, along a length of the sheath, to orient the distal-mostportion of the outer tube for navigation within a venous system of apatient, and the slot opening extends along a length of the pre-formedcurvature.

Deployment of the medical device may be accomplished by moving the outertube in a proximal direction, between first and second positions,relative to the inner subassembly, for example, via a first controlmember of a handle of the delivery system. When the outer tube is in thefirst position, the above-described deflection may be actuated, forexample, via a second control member of the handle; and, when the outertube is moved proximally, or retracted toward the second position, afixation member of the medical device becomes exposed, to engage withtissue in proximity to the target implant site.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of particular embodiments of thepresent invention and therefore do not limit the scope of the invention.The drawings are not to scale (unless so stated) and are intended foruse in conjunction with the explanations in the following detaileddescription. Embodiments will hereinafter be described in conjunctionwith the appended drawings wherein like numerals denote like elements,and:

FIG. 1 is a schematic showing an example of an implanted cardiacstimulation device;

FIG. 2A is a plan view of a delivery system assembly, according to someembodiments;

FIGS. 2B-C are plan views of inner and outer subassemblies,respectively, of the system assembly shown in FIG. 2A, according to someembodiments;

FIG. 3A is a plan view, including cut-away sections, of the deliverysystem assembly, according to some alternate embodiments and with anouter tube thereof in a first position; and

FIG. 3B is a plan view, including a cut-away section, of the assembly ofFIG. 3A with the outer tube in a second position.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is notintended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the following description providespractical examples, and those skilled in the art will recognize thatsome of the examples may have suitable alternatives.

FIG. 2A is a plan view of a delivery system assembly 200, according tosome embodiments; and FIGS. 2B-C are plan views of an inner subassembly220 and an outer subassembly 240, respectively, of system assembly 200.FIG. 2A illustrates system assembly including a handle 210 and anelongate outer tube 230 extending from handle 210 to a distal end 232thereof. According to the illustrated embodiment, outer tube 230 forms alumen (not shown) in which inner subassembly 220 extends; and, it shouldbe understood that, the lumen formed by outer tube 230 preferably has aproximal opening at proximal end 231 and a distal opening at distal end232. FIG. 2B illustrates inner subassembly 220 including an elongatecore 250, an elongate pull-wire 225, which extends along core 250, and asheath 260, which surrounds pull-wire 225 and core 250, for example,over a length of between approximately 12 cm and approximately 18 cm.FIG. 2A further illustrates handle 210 including a first control member211 and a second control member 212. With reference to FIG. 2C, aproximal end 231 of outer tube 230 is shown coupled to first controlmember 211, for example, by a UV cure adhesive; and, with reference toFIG. 2B, a proximal end of pull-wire 51 is shown coupled to secondcontrol member 212, for example, by a UV cure adhesive. According to anexemplary embodiment, pull-wire 225 has a diameter of approximately0.009 inch (˜0.23 mm) and is formed from medical grade 304 stainlesssteel, which is preferably coated with a fluoropolymer such aspolytetrafluoroethylene (PTFE). According to FIG. 2B, core 250 extendsproximally, beyond proximal end 231 of outer tube and second controlmember 212, to a proximal end 251 thereof, which is preferably fixedwithin handle 210 and may be coupled to a luer fitting (not shown), towhich a stop cock 290 is shown coupled in FIG. 2A. According to somepreferred embodiments, control members 211, 212 are slidable alonghandle 210, such that: first control member 211 actuates longitudinalmovement of outer tube, to retract outer tube 230, relative to innersubassembly 220 and handle 210 (FIG. 3B); and second control member 212actuates pull-wire 225 to deflect a flared distal end 252 of core 250,which, in turn, deflects distal end 232 of outer tube 230 (FIG. 3A), forexample, toward a target implant site, prior to the retraction of outertube 230.

Flared distal end 252 of core 250 is preferably configured to conform toa proximal end 121 of implantable medical device 100, for example, asillustrated in FIG. 3A, and, with further reference to FIG. 3A, thelumen of outer tube 230, along a length of a distal-most portion 235 ofouter tube 230, is sized to contain both flared distal end 252 anddevice 100 together, in order to deliver device 100 into proximity withthe target implant site. According to some embodiments, the conformingconfiguration of distal end 252 can help to retain device 100 withindistal-most portion 235 of outer tube 230 during navigation of deliverysystem assembly 200 and prior to deployment of device 100 therefrom.According to an exemplary embodiment, distal-most portion 235 has aninner diameter of approximately 0.275 inch (˜0.7 cm) and an outerdiameter of approximately 0.3 inch (˜0.8 cm). Although FIGS. 2C and 3Aillustrate distal-most portion 235 being enlarged from a remainder ofouter tube 230, for example, over a length of approximately 3.5 cm (˜1.4inch), according to alternate embodiments, an outer diameter along amore significant length up to an entire length of outer tube 230 may bethe same as that of the distal-most portion. According to some preferredembodiments, flared distal end 252 of core 250 is radiopaque and distalend 232 of outer tube 230 is fitted with a radiopaque marker, so thatthe retraction of outer tube 230, relative to flared distal end 252,which will be described in greater detail below, can be observed viafluoroscopy. According to an exemplary embodiment, flared distal end 252is formed from a polyether block amide, for example, PEBAX® 7033, with aradiopaque Barium sulfate filler; and distal-most portion 235 of outertube 230 is formed from a polyether block amide, for example, PEBAX®7233, which, at distal end 232, includes a radiopaque band of 75%Tungsten and 25% PEBAX® 6033 sandwiched between layers of the PEBAX®7233.

FIGS. 2B and 3A illustrate sheath 260 including a slot opening 265 thatis located and sized to allow pull-wire 225 to pass laterallytherethrough. A length of slot 265 may be between approximately 1 cm andapproximately 5 cm, preferably between approximately 2.5 cm andapproximately 3 cm. FIGS. 2B and 3A further illustrates a distal end 62of sheath 260 coupled to core 250 in close proximity to anchored distalend 52 of pull-wire 225, and a proximal end 61 of sheath 260 spacedapart, distally, from handle 210, for example, by a longitudinaldistance y (FIG. 3A), which is between approximately 90 cm andapproximately 100 cm.

FIGS. 2A-C show assembly 200 extending along a relatively straight line,according to some embodiments, but, according to some preferredembodiments, assembly 200 has a pre-formed curvature along a length ofsheath 260, for example, as illustrated in FIG. 3A, wherein the lengthmay be between approximately 6 cm and approximately 20 cm. Withreference to FIG. 3A, the pre-formed curvature extends about a radius rof between approximately 9 cm and approximately 13 cm, and orientsdistal-most portion 235 at an angle θ of approximately 120 degrees withrespect to a length of assembly 200 that extends proximal to thepre-formed curve. The radius of curvature r and angle θ can facilitatethe navigation of delivery system assembly 200 within a venous system ofa patient, for example, by orienting distal-most portion 235 of outertube 230 for passage from the RA, through the tricuspid valve, into theRV (FIG. 1). With further reference to FIG. 3A, pull-wire 225 is shownextending laterally through slot opening 265. According to theillustrated embodiment, when second control member 212 is moved, perarrow P, pull-wire 225 is actuated to deflect distal end 252 of core250, along with distal end 232 of outer tube 230, per arrow D, into atighter radius, for example, so that the distal opening of the lumen ofouter tube 230 may be directed toward a target implant site fordeployment of the contained medical device 100 therethrough, forexample, by retraction of outer tube 230, relative to inner subassembly200, as described below. According to an exemplary embodiment, core 250extends over a length of approximately 118 cm, from proximal end 251 tojust proximal to flared distal end 252, has an outer diameter ofapproximately 0.112 inch (˜2.85 mm), and is formed from a stainlesssteel braid (0.0012″×0.003″×70 PPI) surrounding a polyether block amidePEBAX® 7033 liner, and overlaid, along a proximal section (having alength of approximately 108 cm), with a layer of Trogamid® polyamide,and, along a distal section (having a length of approximately 10 cm),with a layer of Vestamid® polyamide. In this exemplary embodiment,sheath 260 is formed from a polyether block amide PEBAX® 5533, which hasa durometer, on a shore D scale, of between approximately 50 andapproximately 55. Although FIG. 2B shows a length of pull-wire 225,which extends proximally from sheath 260 to proximal end 51,unconstrained alongside core 250, according to some alternateembodiments, a lumen, for example, having a diameter of approximately0.015 inch (˜38 mm), extends along the wall of core 250 to contain thislength of pull-wire 225. FIGS. 2B and 3A show a distal end 52 ofpull-wire 225 anchored to core 250 in proximity to flared distal end252, for example, by thermal bonding within the polymer melt that formsthe junction between sheath 260 and flared distal end 252. Although notshown, distal end 52 of pull-wire 225 may be terminated by a ring orband that is thermally bonded within, or in close proximity to thejunction between sheath 260 and distal end 252. For those embodiments inwhich assembly 200 has the pre-formed curvature, the curvature may beformed by heat setting, according to methods known to those skilled inthe art of catheter construction. The curvature may be pre-formed intoinner subassembly 220, prior to inserting subassembly 220 within thelumen of outer tube 230, or the curvature may be pre-formed into outertube 230, prior to assembling inner subassembly 220 therein.

The construction of outer tube 230 may be any suitable type known in theart to achieve a graduated flexibility that accommodates deflection inresponse to the deflection of core 250, for example, as described above,and to achieve the necessary pushability and torque transfer thatfacilitates the maneuverability of delivery system assembly 200 to atarget implant site, as will be described in greater detail below.According to an exemplary embodiment, outer tube 230 includes a braidreinforced liner, for example, PEBAX® 6333 with a stainless steel braid(i.e. 0.0018″×0.008″×45 PPI) extending from proximal end 231 to justproximal to distal-most portion 235 of outer tube 230; a proximalsegment of the shaft is overlaid with PEBAX® 7033 and extends over alength of approximately 92 cm (a proximal portion of which length isalways contained within handle 210); an intermediary segment of theshaft is overlaid with PEBAX®4033 and extends distally from the proximalsegment over a length of approximately 10 cm; and a distal segment ofthe shaft is overlaid with PEBAX® 3533 and extends distally from theintermediary segment, over a length of approximately 3 cm, to justproximal to the distal-most portion. Outer and inner diameters of outertube 230, along the above-described segments, may be approximately 0.187inch (˜4.75 mm) and approximately 0.154 inch (˜3.91 mm), respectively.

With further reference to FIG. 3A, while delivery system assembly 200 isbeing advanced within a patient's venous system and maneuvered intoproximity to the target implant site, for example, within the RV (FIG.1), and while second control member 212 is moved, per arrow P, toactuate the deflection, per arrow D, via pull-wire 225, outer tube 230generally remains in a first position 31 relative to core 250, so thatan entirety of device 100 is contained within distal-most portion 235.According to some preferred embodiments, a longitudinal distance betweenhandle 210 and distal end 231 of outer tube 230, when outer tube 230 isin first position 31, is between approximately 103 cm and approximately107 cm, for example, to reach the RV from a femoral access site. Oncedeflected, so that distal end 232 of outer tube 230 is adjacent thetarget implant site, first control member 211 is moved, per arrow M, asillustrated in FIG. 3B, to retract outer tube 230 longitudinally,relative to core 250, from first position 31 to a second position 32,per arrow R. According to the illustrated embodiment, the retraction ofouter tube 230 exposes fixation member 115 of device 100, which passesoutside distal-most portion 235, through the distal opening of the lumenof outer tube 230, for engagement within tissue at the target implantsite. According to some embodiments, an O-ring type seal member (i.e.silicone; not shown), which may be lubricated, for example, withsilicone oil, forms a dynamic sealing interface between outer tube 230and core 250 within handle 210, in proximity to first control member211.

The above-described conforming configuration of flared distal end 252may help to retain a temporary connection between device 100 anddelivery system assembly 200 until fixation member 115 becomes engagedwith the tissue; but, according to some preferred embodiments, device100 is further secured to system assembly 200 by a tether, which isremovably attached to proximal end 121 of device 100, for example, asdescribed in the above-referenced related U.S. patent application Ser.No. 13/279,835. Another of the above-referenced related applications,U.S. patent application Ser. No. 13/219,279, describes some alternateconfigurations of proximal end 121 of device 100 that may be employedfor tether attachment. Although FIG. 3A illustrates distal end 232 ofouter tube 230 approximately aligned with flared distal end 252 of core250, when outer tube 230 is in second position 32, second position 32may be located more proximally, such that more of core 250 is exposeddistal to distal end 232 of outer tube 230, or more distally, such thatonly fixation member 115 of device 100 is exposed. According to FIG. 3B,an entirety of device 100 is exposed when outer 230 is in secondposition 32; thus, a longitudinal distance between first position 31 andsecond position 32 may be as small as approximately 2 cm up toapproximately 6 cm, depending on the length of device 100. Alternately,second position 32, as mentioned above, may be located to only expose aportion of device 100, for example, enough of fixation member 115 tosecure device 100 at the implant site, in which case, the longitudinaldistance between the first and second positions may be as small asapproximately 0.5 cm to 1 cm.

With further reference to FIG. 2A, delivery system assembly 200 furtherincludes an optional overlay 275, which is shown surrounding outer tube230, in proximity to handle 210. Optional overlay 275 provides anenhanced interface between system assembly 200 and a valve of anintroducer sheath, which is used to introduce system assembly 200 intothe patient's venous system, to facilitate the above-describedlongitudinal movement of outer tube 230 relative to core 250 and handle210. For example, the enhanced interface provides improved sealingand/or additional radial strength to counteract a compressive force ofthe valve, which, if the valve is a Tuohy Borst type, can be tighteneddown around system assembly 200 to different degrees depending upon theoperator. Optional overlay 275 is preferably slidable over outer tube230 so that overlay 275 may be repositioned with respect to handle 210in order to coincide with the valve of the introducer sheath. Accordingto an exemplary embodiment, optional overlay 275 is formed from apolyether block amide, for example, PEBAX® 7030, which may include atitanium oxide filler. Such an overlay is described in theabove-referenced related U.S. patent application Ser. No. 13/239,990,the description of which is hereby incorporated by reference. It shouldbe noted that, although not shown, delivery system assembly 200 mayalternately, or in addition, include an outer stability sheath like thestability sheath (250) that is described in the immediatelyaforementioned related application, the description of which is alsoincorporated by reference.

In the foregoing detailed description, the invention has been describedwith reference to specific embodiments. However, it may be appreciatedthat various modifications and changes can be made without departingfrom the scope of the invention as set forth in the appended claims.

The invention claimed is:
 1. A delivery system assembly facilitatingdeployment of an implantable medical device, the assembly comprising: anelongate outer tube extending from a proximal end thereof to adistal-most portion thereof, the outer tube forming a lumen that extendsfrom a proximal opening thereof at the proximal end of the outer tube toa distal opening thereof that terminates the distal-most portion of theouter tube, the distal-most portion being sized to contain an entiretyof the implantable medical device therein; an inner subassemblyextending within the lumen formed by the outer tube, the innersubassembly including an elongate core, a pull-wire and a sheath thatextends around the pull-wire and the core, the core including a proximalend, positioned proximal to the proximal end of the outer tube, and aflared distal end being configured to conform to a proximal end of themedical device such that the distal end of the core fits, along with theentirety of the medical device, within the distal-most portion of theouter tube, the pull-wire extending along the core and including adistal end anchored to the core in close proximity to the flared distalend thereof, and the sheath extending from a proximal end thereof to adistal end thereof, the proximal end of the sheath being spaced apart,distally, from the proximal end of the outer tube, and the distal endcoupled to the core in close proximity to the anchored distal end of thepull-wire, the sheath including a slot opening formed therein, and theslot opening being sized to allow the pull-wire to pass laterallytherethrough; wherein the assembly has a pre-formed curvature, along alength of the sheath, and the slot opening of the sheath extends alongthe pre-formed curvature; and the outer tube is longitudinally moveablerelative to the inner subassembly.
 2. The assembly of claim 1, whereinthe pre-formed curvature extends about a radius of between approximately9 cm and approximately 13 cm, and the distal-most portion of the outertube is oriented, by the curvature, at an angle of approximately 120degrees with respect to a length of the assembly that extends proximalto the pre-formed curvature.
 3. The assembly of claim 1, wherein alength of the slot opening of the sheath of the inner subassembly isbetween approximately 2.5 cm and approximately 3 cm.
 4. The assembly ofclaim 1, wherein the sheath of the inner subassembly has a length ofbetween approximately 12 cm and approximately 18 cm, and the proximalend of the sheath is spaced distally apart from the proximal end of theouter tube by a longitudinal distance of between approximately 90 cm andapproximately 100 cm.
 5. The assembly of claim 1, wherein the elongatecore of the inner subassembly is formed from a braid reinforced polymercomprising a polyether block amide and a polyamide; and the sheath isformed from a polyether block amide having a hardness in a range ofapproximately 50 to approximately 55 on a shore D scale.
 6. The assemblyof claim 1, wherein the flared distal end of the core of the innersubassembly is radiopaque.